This invention is an improved wheelchair that can be collapsed and unfolded by a seated user and stored in a limited space such as the overhead luggage carrier of an airplane, and that is readily converted by the seated user or another person into a caster chair.
Handicapped persons differ greatly in their ability to get about. Some may be incapable of walking and thus confined to wheelchairs, while others may be partially ambulatory. Moreover, the mobility of a handicapped person may vary throughout the course of the handicap, week by week or even day by day, and the quality of life for such a person is affected greatly by his or her mobility.
Wheelchairs are commonly used by such persons to increase their mobility, either alone or with the assistance of others. Many conventional wheelchairs are easily collapsible but are characterized by heavy-duty construction to provide safe and stable transport for persons of different weights and sizes over varying terrain. As a result, the wheelchair user will typically require the assistance of another to collapse a wheelchair and load it into and unload it from a car for storage purposes. A further inconvenience is that the typical wheelchair is not easily folded by an unassisted wheelchair user. The typical wheelchair is too large to go through the doorways of many residential bathrooms, making it very difficult for the wheelchair user to have independent access to the bathroom. Finally, most of these wheelchairs are not adapted for multiple uses.
U.S. Pat. No. 2,561,616, entitled "Convertible Wheel Chair", discloses a conventional wheelchair in which the large drive wheels and front caster wheels may be interchanged to permit easier operation and maneuverability as required by changes of grade and obstacles such as curbs and stairs. This wheelchair has several advantages over conventional prior art wheelchairs, including removable drive wheels and the substitution of casters in their place. The drive wheels are mounted and dismounted by means of axles having internally threaded extensions and thimbles. In the alternative, the drive wheels may be eliminated and replaced with smaller caster wheels to convert the wheelchair to a caster chair. Although this wheelchair has the advantage of convertibility, it requires a time-consuming and dexterity-intensive election of a particular wheel-caster combination, and thus is not readily convertible from one configuration to another by a handicapped user.
The advantage of a caster chair in certain circumstances is disclosed in U.S. Pat. No. 4,052,087, entitled "Foldable Caster Chair for the Handicapped". This patent points out the utility of the foldable caster chair for some uses such as in an office and using a toilet. An objective of the patent is to allow for the rotation of the side arms away from the seating area to allow easier use of toilet facilities.
Wheelchairs have been adapted to be user-adjustable by the manipulation of hydraulic or electric controls. An example of such a wheelchair is described in U.S. Pat. No. 3,618,968, entitled "Patient Operated Wheelchair". This wheelchair has front and rear caster wheels for stability and two centrally mounted large drive wheels for patient locomotion. It is adjustable hydraulically, and may be converted into a stretcher, in which case the weight is borne by the rear casters. The front and rear casters do not contact the ground at the same time. Such wheelchairs have the disadvantage of restricted portability attributed to the added weight of the adjustment mechanism.
More recently, wheelchairs have been made with aircraft alloys, racing bicycle components, and the like, utilizing polymers and composite materials, and features such as raked wheels, to achieve lighter, faster, and more stable manually propelled wheelchairs. These chairs and their users have improved the general perception of wheelchairs and the handicapped. Such wheelchairs, while representing significant improvements in wheelchair technology in their own right, do not readily lend themselves to use in performing many routine but nevertheless necessary domestic functions. Their stability despite their light weight is attained at the expense of a wider wheelbase, greater length, and a lower seating position that is not well suited for mobility around the home and work place.
Those who have used conventional wheelchairs, and those who have observed handicapped persons attempt to use wheelchairs in spaces not designed for them, are aware that the large drive wheels often limit the choice of passageways which are accessible to the wheelchair user, especially on airplanes and in restaurants. Even in a barrier-free environment, unassisted maneuvering from a conventional wheelchair to a toilet can be a daunting task.
U.S. Pat. No. 3,887,228 describes a kit for converting a folding lawn chair into a wheelchair. This results in an extremely lightweight, highly portable wheelchair. The drawbacks of the resulting wheelchair are associated with the inherent design characteristics of these familiar backyard lawn chairs. For example, the integral arm rests which are structurally required to support the chair frame prevent the handicapped user from sliding sideways from the chair to the bed or the toilet. Another drawback of the lawn chair is that it tends to collapse if the user attempts to place his or her weight upon the backrest for support while standing.
Conventional wheelchairs require a vigorous lifting of the seat to fold. While this motion is relatively simple for a strong adult who is standing, it is virtually impossible for the handicapped wheelchair user to accomplish without assistance.
Lightweight, collapsible, inexpensive, transportable chairs with wheels have been designed for use as infant strollers. The inherent characteristics of these chairs makes them unsuitable for adaptation as wheelchairs even for small adults. Such wheelchairs are designed to support only light loads. Furthermore, the foldable frames have centers of gravity located over the rear wheels to make it easier for one pushing the wheelchair to negotiate curbs and stairs. This makes it difficult, if not impossible, for the chair to be manually self-propelled.
Many handicapped people are, or may with rehabilitation become, at least partially ambulatory. Self-reliance and independence is an extremely important aspect of the rehabilitation process and, to the extent further rehabilitation is not possible, of living with the handicap. It is to this need that the present invention is directed.